There exist systems for controlling the brightness of light sources dependent on the light intensity emitted from other light sources. Known systems comprise an external light dimmer for a manual regulation of the light source. Other known systems make use of additional “twilight switch electronics” that have to be shadowed from the radiation of the regulated light source. In such systems the light sensor is influenced by the regulated light source itself, if they are positioned together in the range of influence at the same place. For avoiding mutual influence of the light sensor and the regulated light source, high additional efforts of external electronic control and of additional wiring, and thus additional costs had been necessary.
In other known systems for regulating light sources for vehicles, the light emission of the light source is controlled independently from artificial light sources using filters to block the light emitted from the controlled light source to fall into a light sensible sensor. Due to the filter the known system is a complicated construction and is restricted to a discrete selection of the light passing through the used filter.